(1) Field of the Invention
The present invention relates to a process for connecting sheet metal panels and the like coated on at least one surface with layer such as an ainsulating layer by the electrical fusion of metal, and to an apparatus for carrying out said process.
(2) Description of the Prior Art
Sheet metal panels coated, for instance, with an insulating coating such as with a plastic layer are known for many years. Due to their rust-free, insensitive surfaces such panels are available in many different patterns and colors. It is well known, however, that such metal panels cannot be connected to each other and interwelded economically with themselves or other metallic parts by spot- or roller-welding in the usual manner.
The present applicant has suggested to strip the sheet metal panels at the places to be welded in such a manner than an electrical contact is established when the sheet metal panels are pressed upon each other. With comparatively thick layers of plastic and the like insulating material and likewise with comparatively thick sheet metal panels and cavities formed by stripping the coating layers may be filled by inserted intermediate welding pieces. In this manner faultless welded connections can be produced with the usual welding machines on sheets of steel, chromium-nickel steel, aluminum or other metals coated with plastics, lacquers, or other materials, or having an oxide layer thereon. However, thereby the outer coatings of the stripped sheet metal panels are destroyed by stripping or melting under the electrodes.